This invention pertains to a radiation-curable silicon-containing composition which can be used for example, in the manufacture of insulating films for semiconductor devices and to a method for manufacturing patterns consisting of a cured silicone product and inorganic silicon oxide utilizing said composition.
It is known in the art that hydrogen atoms bonded directly to silicon atoms will react with the hydroxy groups of water, alcohols or silanols, to form hydrogen molecules and silicon-oxygen bonds, Si--O. At high temperatures, this reaction will proceed even without a catalyst however, it is known that the reaction proceeds more readily in the presence of transition metal catalysts such as platinum or palladium; basic catalysts such as alkali metal hydroxides or amines; or Lewis acid catalysts such as tin compounds. Furthermore, it has been proposed that cross-linking reactions involving Si--H and SiOH may be used in room-temperature curing reactions of silicones.
Curing reactions utilizing the effects of radiation, and techniques associated with such reactions, are known in the art. Examples of the curing using the effects of radiation include curing based on crosslinking reactions and curing based on polymerization reactions.
Examples of curing based on crosslinking reactions include curing utilizing photo-dimerization reactions of cinnamic acid compounds, curing utilizing reactions between mercapto groups and olefins, and curing utilizing diazo groups or azide groups as photosensitive groups.
Examples of curing based on polymerization reactions include combining functional groups such as acryloyl groups or methacryloyl groups with polymerization initiators that generate radicals when exposed to radiation, and methods in which cationic polymerization initiators are generated by irradiation with radiation. The cationic polymerization of epoxy groups, lactones or active vinyl groups, is performed using these initiators.
There are also curing methods which use an acid-generating substance that generates an acid when irradiated with radiation, and which cause a cross-linking reaction or polymerization reaction to take place through the catalytic action of the acid produced. For example, Japanese Patent Application Kokai No. 6-80879 discloses methods for manufacturing thin films of silicate glass by combining specified siloxanes with substances that generate acids when exposed to the effects of radiation. Japanese Patent Application Kokai No. 58-174418 discloses techniques for the photo-curing of epoxy resins using aluminum compounds and o-nitrobenzoyloxysilicon compounds. Acid generating substances known in the art include use aryldiazonium salts diaryliodonium salts, triarylsulfonium salts triarylselenium salts, dialkylphenacylsulfonium salts, dialkyl-4-hydroxyphenylsulfonium salts, sulfonic acid esters, iron-allene compounds, and silanol-aluminum complexes.
There are also several methods known in the art in which the curing reaction is effected using a substance which generates a base when irradiated with radiation. Base-generating substances used in such methods include organic and inorganic nitrogen-containing compounds such as o-nitrobenzyl carbamate compounds, metal-amine complexes and 4-(o-nitrophenyl)dihydropyridines. Organic amines, ammonia or quaternary ammonium hydroxides are irradiated with radiation.
In the base-generating methods the base that is generated acts as a catalyst in the cross-linking reaction and an amplifying effect is obtained in the cross-linking reaction even if the intensity of the radiation is low, and unlike the case of radical reactions, there is no oxygen interference. Furthermore, compared to methods which use an acid, methods which use a base are advantageous in that there is little problem of substrate corrosion. However, the application of such methods is extremely limited. For example, EP 0555749 A1 discloses a method in which compositions consisting of a phenol resin, epoxy cross-linking agent and melamine curing agent are cured using a basic catalyst generated.
Japanese Patent Application Kokai No. 6-148887 discloses a method in which polysilsesquioxanes alone, and compositions consisting of polysilsesquioxanes and tetraphenoxysilane are cured. In JP'887 the sensitivity (D50=amount of irradiation producing a residual film rate of 50% in the developing process) is extremely low. Additionally, it appears that curing is attributable to a condensation reaction in which water, alcohols or phenols are produced as by-products, so that there is a large weight reduction accompanying curing.
Japanese Patent Application Kokai 6-273936 discloses a photosensitive resin composition using a siloxane polymer and a base-generating agent, and a pattern forming method using this composition. In JP '936 the sensitivity (D50) is not reported; however, the amount of irradiation is 100 mJ/cm.sup.2 to 300 mJ/cm.sup.2 (365 nm), so it appears that the sensitivity is low. Additionally, the curing appears to be based on a condensation reaction in which water or alcohols are produced as by-products, so that curing is accompanied by considerable weight reduction and shrinkage.
In both of the examples mentioned above, it is believed that the extremely low sensitivity is attributable to the characteristics of the condensation reaction itself.
It is an object of the present invention is to provide a silicon-containing composition with good patterning characteristics, which shows little weight reduction or shrinkage accompanying curing, and which has good storage stability
It is further an object of the present invention to provide a pattern forming method using said composition.